Are you saying his sound got more "white" as he progressed?
Well first off, I don't think Chuck Berry's sound ever progressed much at all. He played what he played and it never really changed too much.
And what I'm saying is was what I posted: Berry's sound had more influence on white, guitar-driven rock music than on black R&B music. There were a lot more white kids picking up guitars and trying to sound like Chuck Berry than there were black kids.
But when Chuck Berry started, his music was considered "race music" or "black music", alongside Bo Diddley: guitar-driven blues (like BB King or Jimmy Reed) sped up with a swing beat (like Big Joe Turner). He also established the guitar as the predominant instrument in rock music, which previously had been the saxophone (listen to Bill Haley or other early rock acts, and you'll hear saxophones doing what would become the guitar solos). Other rock pioneers like Little Richard and Fats Domino were piano players, and so it was Berry and Diddley that brought the guitar to prominence. Of course, this is a simplified history, but it's true.